The explosive growth in wireless applications and devices over the past few years has produced tremendous public interest benefits. Wireless networks and devices have been deployed in millions of offices, homes, and more recently, in increasing numbers of public areas. These wireless deployments are forecast to continue at an exciting pace and offer the promise of increased convenience and productivity.
This growth, which is taking place mostly in the unlicensed bands, is not without its downsides. In the United States, the unlicensed bands established by the FCC consist of large portions of spectrum at 2.4 GHz and at 5 GHz, which are free to use. The FCC currently sets requirements for the unlicensed bands such as limits on transmit power spectral density and limits on antenna gain. It is well recognized that as unlicensed band devices become more popular and their density in a given area increases, a “tragedy of the commons” effect will often become apparent and overall wireless utility (and user satisfaction) will collapse. This phenomenon has already been observed in environments that have a high density of wireless devices.
The types of signaling protocols used by devices in the unlicensed bands are not designed to cooperate with signals of other types also operating in the bands. For example, a frequency hopping signal (e.g., a signal emitted from a device that uses the Bluetooth™ communication protocol or a signal emitted from certain cordless phones) may hop into the frequency channel of an IEEE 802.11 wireless local area network (WLAN), causing interference with operation of the WLAN. Thus, technology is needed to exploit all of the benefits of the unlicensed band without degrading the level of service that users expect.
Historically, the wireless industry's general approach to solving “tragedy of the commons” problems has been for manufacturers to simply move to another commons further up the spectrum. This solution, however, is not workable for much longer, due to spectrum scarcity and to the less attractive technical characteristics of the higher bands (decreased signal propagation and the inability to penetrate surfaces).
Enterprise uses of the unlicensed band are focused on larger scale deployment of wireless networks (e.g., WLANs) and integration into wired networks. WLANs can complicate existing network management schemes because they introduce the additional requirement of efficiently managing radio spectrum. Current WLAN systems and management technology are focused on managing activity at the network level of the WLAN, but provide little of no capability to manage the frequency band where signals of multiple types (e.g., communication protocol/network types, device types, etc.) are present. What is needed is technology to obtain and use knowledge of what is happening in a shared radio frequency band, such as an unlicensed band, to enable devices to act intelligently with respect to their use of the frequency thereby maintaining the performance of devices and networks of devices operating in that frequency band.